A theoretical model for immobilized enzyme inhibition biosensors

作者：Zhang SQ; Zhao HJ^*; John R

来源：Electroanalysis, 2001, 13(18): 1528-1534.

DOI：10.1002/1521-4109(200112)13:18<1528::AID-ELAN1528>3.0.CO;2-1

• biosensors
• enzyme inhibition
• microelectrode array
• paraoxon
• pesticides
• acetylcholinesterase
• choline oxidase

The development and experimental verification of a theoretical model for immobilized enzyme inhibition biosensors is reported. The model predicts that the percentage of inhibited enzyme (I%), after exposure to air inhibitor, is linearly related to both die inhibitor concentration ([I](B)) and the square root of incubation time (t(1/2)):
I% = Kt(1/2)[I](B) x 100
The model is based on diffusion limited inhibitor transport and takes into account the heterogeneous nature of enzyme inhibition that results from immobilization of an enzyme at the surface of a transducer. Experimental verification of the model A as achieved using an electrochemical (amperometric) acetylcholine sensor, The immobilized enzyme used in this study was acetylcholinesterase, while die organophosphorus pesticide. paraoxon, was employed as the inhibitor. A second enzyme, choline oxidase, was co-immobilized to facilitate electrochemical detection of the substrate. To satisfy the conditions required by the proposed model a specially designed biosensing device was fabricated employing a microdisk array as the transducer, Acetylcholinesterase (0.00025 units) and choline (1.0 units) were co-immobilized onto die array using a water-based polyurethane/polyethlene oxide colloidal dispersion matrix. A dialysis membrane was used as an active barrier to present fouling of the array and to restrict enzyme leaching. The device vas used for both batch and flow injection analysis and experimental results verifying the proposed model are presented using both modes.

• 出版日期2001-12